/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineSessionInterface.h
virtual void TriggerOnSessionParticipantsChangeDelegates ( [FName](API\Runtime\Core\UObject\FName) Param1, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & Param2, bool Param3 )